Tensioning device



June 1967 .J. NIXDORF ETAL.

TENSIONING DEVICE Filed April 15, 1965 5. COMPRESSED AIR United States Patent 3,323,754 TENSIONING DEVICE Joachim Nixdorf and Alfred Biirgel, Frankfurt am Main,

Germany, assignors to The Federal Republic of Germany as represented by the Secretary of Defense, Bonn, Germany Filed Apr. 15, 1965, Ser. No. 448,542 Claims priority, application Germany, Apr. 25, 1964, B 76,507 4 Claims. (Cl. 242147) This invention relates to a method and apparatus for controlling tension in wires and filaments as they are wound from one package to another.

It is known to draw wires of extremely fine gauge, i.e. wires having a diameter of less than about 10 from a melt. Thereby, such wires are wound upon a drum having a diameter which is very large in relation to the wire diameter. For shipping, the wire must be spooled upon smaller carriers, and for such rewinding, proper tension of the wire must be maintained. All attempts to apply such tension by means of springs, or small weighted rollers rolling on the wire, have failed because the produced tension exceeded the tensile strength of the wire or because the wire was damaged.

It is, therefore, a principal object of the invention to provide an improved tension controlling apparatus for micro-fine wires and filaments of any material.

Other objects and advantages will be apparent from a consideration of the specification and claims.

The present invention avoids the difliculties associated with the conventional tension control devices 'by providing, below the wire or filament drawn off a reel, a tube which is disposed in a direction transversally to the direction of the path of the drawn filament and closed at one end, while the other end is connected to a pressure gas line. On a line parallel to the axis and along the crest of the circumference, said tube is provided with a plurality of aligned spaced small apertures whose diameters increase from the center towards the ends and whose total cross sectional area is smaller than the cross section of the tube.

Preferably, the proportion of said cross section of the tube to the sum of the cross sectional areas of all said apertures is in the range of about 30:1 to 3:1; in other words, the cross section of the tube is always considerably larger than the total area of all the outlet openings.

The outermost, i.e. the largest outlet opening; has a cross sectional area which is about A to A of the cross section of the tube. The smallest outlet opening, i.e. the aperture at the center of the tube, has an area which is about to 20 times smaller than the largest opening. The number of outlets may be 3 to 12 for any 4 inch length of the tube.

Gas or air blown out from said row of outlets lifts the wire or filament passing above the tube and tenses the same as a function of the number and size of the gas outlets and of the gas pressure. The tension is readily adjusted by adjusting the gas pressure. As the filament does not come in frictional contact with any surfaces, this method of tensioning avoids the risk of injury to the surface of the filament.

In addition, the device makes it possible to form a large 3,323,754 Patented June 6, 1967 "ice loop of the filament between the supply reel and the takeup spool; this reduces considerably the risk of breakage if, for some reason, the synchronism of reel and spool should be temporarily disturbed.

A preferred embodiment of the invention will now be described with reference to the accompanying drawing showing a diagrammatic View of a tension control assembly incorporating the apparatus of the invention.

Referring to the drawing, it will be seen that the direction of drawing of the microfine wire 1 is perpendicular to the plane of the drawing. Tube 2 has a length of 280 mm., an outer diameter of 16 mm. and an inner diameter of 14 mm. It has 26 apertures spaced from each other by 10 mm. whereby the diameter of said apertures increases from 0.7 mm. for the center outlet to 1.6 mm. for the outlets closest to the ends. The total cross-sectional area of the outlets is 22.33 mm. The cross-sectional area of the tube is 154.0 mm. the ratio of the cross-sectional area of the outlets to the cross-sectional area of the tube is, therefore, 126.9.

Compressed air or gas is introduced into the tube 2 and flows out of the outlets 3. As the outlets have an increasingly larger size from the center of the tube towards the ends, the gas jets delivered through said outlets have a correspondingly increasing range, thereby forming a parabolic flow profile as indicated in the drawing in broken lines.

The outflowing air or gas deflects upwardly the wire traveling from the supply reel to the spool. The amount of upward deflection is controlled by the gas pressure in the tube. The parabolic flow profile prevents the wire from shifting laterally when raised because it will always fall back into the vertex of the parabola when it should start rising along the ascending branches of the flow profile.

The vertical distance of the wire or filament from the tube can be varied in accordance with the size of the desired loop and will depend essentially on the gas pressure in the tube and on the size and number of the gas outlets.

We claim:

1. An apparatus for tensioning ultrafine filamentary material prior to winding comprising means supplying said filamentary material, rotatable means receiving said filamentary material, a substantially horizontal tube having an open end and a closed end and being disposed below, and transversally of, the path of said filamentary material from said supply to said receiving means, and pressure gas supplying means connected to said open end of the tube, said tube being provided along its highest cir cumferential line extending parallel to its axis with a plurality of aligned spaced apertures, the diameter of said apertures increasing from the middle of said tube towards the ends of the tube and the total cross sectional area of said apertures being smaller than the cross section of said tube.

2. A method for substantially frictionless tensioning 0f ultrafine filamentary material prior to winding, which method comprises providing a row of upwardly directed parallel aligned gas jets, the lifting force of said jets increasing from the jets in the middle of said row towards both ends of said row so as to form a flow profile having the approximate shape of a parabola whose vertex is the lowest point, passing said ultrafine filamentary material across said row of jets in a direction of travel substantially at a right angle to said row, thereby lifting said filamentary material to form a loop, and controlling the size of said loop, and therewith the tension of the fila mentary material, by the force of said jets.

3. The method as claimed in claim 2 wherein said filamentary material is supplied from a level below said row of jets.

4. The method as claimed in claim 2 wherein the lifting force of said jets is increased symmetrically from the middle of the row towards both ends.

4 References Cited UNITED STATES PATENTS FOREIGN PATENTS 3/ 1957 France. 11/ 1961 France.

STANLEY N. GILREATH, Primary Examiner. 

1. AN APPARATUS FOR TENSIONING ULTARFINE FILAMENTARY MATERIAL PRIOR TO WINDING COMPRISING MEANS SUPPLYING SAID FILAMENTARY MATERIAL, ROTATABLE MEANS RECEIVING SAID FILAMENTARY MATERIAL, A SUBSTANTIALLY HORIZONTAL TUBE HAVING AN OPEN END AND A CLOSED END AND BEIGN DISPOSED BELOW, AND TRANSVERSALLY OF, THE PATH OF SAID FILAMENTARY MATERIAL FROM SAID SUPPLY TO SAID RECEIVING MEANS, AND PRESSURE GAS SUPPLYING MEANS CONNECTED TO SAID OPEN END OF THE TUBE, SAID TUBE BEING PROVIDED ALONG ITS HIGHEST CIRCUMFERENTIAL LINE EXTENDING PARALLEL TO ITS AXIS WITH A PLURALITY OF ALIGNED SPACED APERTURES, THE DIAMETER OF SAID APERTURES INCREASING FROM THE MIDDLE OF SAID TUBE TOWARDS THE ENDS OF THE TUBE AND THE TOTAL CROSS SECTIONAL AREA OF SAID APERTURES BEING SMALLER THAN THE CROSS SECTION OF SAID TUBE. 